Johnson & Johnson has informed the FDA that its Evra birth control patch may double the risk of blood clots. The patch contains a higher dose of estrogen than is found in the pill form of the same product. The FDA had expressed its concerns about the patch last year, and asked for additional studies. Now there’s data from 200,000 patients in a JNJ database and from Ingenix, a firm specializing in the analysis of safety trends. But there is no evidence that the clots lead to heart attack or strokes, according to JNJ.